Self regulating fluid bearing high pressure rotary nozzle

ABSTRACT

A fluid bearing nozzle assembly is disclosed that has a hollow cylindrical body, an inlet nut fastened to the cylindrical body, and a hollow tubular shaft member coaxially carried within the housing body and captured between the inlet nut and the body. The inlet nut has a stem portion extending into a central bore through the shaft member forming an inlet bearing area rotatably carrying the shaft member thereon. The shaft member has a spray head fastened thereto for rotation of the head with the shaft member. An inner wall of the housing body and an outer portion of the shaft have complementary shapes forming a regulating passage therebetween. The shaft has helical grooves that spiral around the shaft to one or both ends to impart rotation to the shaft and spray head.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/829,661, filed Jul. 2, 2010, same Title, which application claims thebenefit of priority to U.S. Provisional Patent Application Ser. No.61/259,944, filed Nov. 10, 2009. These applications are incorporated byreference in their entirety.

BACKGROUND OF THE DISCLOSURE

A high pressure rotary nozzle device having a rotating shaft isdisclosed in my U.S. Pat. No. 7,635,096, which is incorporated herein byreference in its entirety. The hollow shaft in this device rotateswithin a fixed housing wherein the axial force which acts upon the shaftdue to the fluid pressure at the shaft inlet is balanced, eliminatingthe need for mechanical bearings.

This nozzle is particularly well suited to industrial uses where theoperating parameters can be in the range of 1,000 to 40,000 psi,rotating speeds of 1000 rpm or more and flow rates of 2 to 50 gpm. Thehollow shaft in this device is provided with a “bleed hole” leading fromthe central bore through the hollow shaft to its exterior. This allows asmall portion of pressurized fluid to reach a chamber formed within thenozzle housing outside the exterior of the forward portion of the nozzleshaft. The fluid pressure in this chamber acts upon the nozzle shaftwith a sufficient axial component so as to balance the correspondingaxial component against the nozzle shaft created by the internal fluidpressure. This chamber, or passage has a frusto-conical tubular shapesurrounding a corresponding tapered portion of the shaft which furtherallows the fluid to flow between the nozzle housing and the shaft tofacilitate and lubricate the shaft as it rotates.

Because of the frusto-conical tapered shape of both the exterior surfaceof the shaft and the complementary interior surface of the housing, thespacing between the housing and the shaft varies slightly with axialmovement of the shaft. This movement creates a self balancing effect inwhich the axial forces upon the shaft remain balanced and there isalways some fluid flowing between the shaft and housing which helpsdecrease contact and resulting wear between these two components.

The rotation of such a nozzle is provided by the reaction forcesexperienced by the nozzle tip as a result of the redirection of fluidflow outward through offset angled ports in the nozzle tip offset fromthe longitudinal axis of the nozzle. The redirection of flow is offsetfrom the axis of the nozzle shaft such that the reaction forces apply atorque to the nozzle shaft and tip. At such high pressures the offsetangled ports are more than sufficient to provide rotation, or swivel, ofthe nozzle about its longitudinal axis. A small detachable jet headhaving a diameter smaller than the body of the nozzle can be attached atthe leading end of the nozzle to provide an improved coverage patternfor the high-pressure fluid.

Unless the nozzle tip, i.e., the jet head, has offset angled ports,rotation of the nozzle shaft is not likely to occur. There are someapplications, however, where offset angled ports are either undesirabledue to a change in driving torque when pressure or flow rate is changed,and undesirable because driving rotation by this method produces veryhigh rotation speeds (20,000-30,000 rpm), Thus there is also a need fora rotary nozzle that is axially self balanced as above described, but inwhich the rotary nozzle shaft is driven by a method resulting in slowerrotation speeds, in a range on the order of 2000 to 4000 rpm, ratherthan relying on offset angled reaction forces to provide the rotationalforce on the nozzle shaft.

SUMMARY OF THE DISCLOSURE

A nozzle in accordance with the present disclosure provides a simplifiedstructure which effectively balances any axial thrust force, withoutneed for mechanical bearings, while at the same time imparting arotational force to cause rotation of the nozzle without requiringoffset nozzle ports.

One embodiment of such a nozzle device has a generally cylindricaloverall outer shape so that it can be inserted into pipes and othertubular passages. The device has a hollow tubular housing body fastenedto a high pressure inlet. Captured between the tubular body and theinlet nut is a hollow, tapered, rotatable swivel shaft. This shaft isrotatably supported on a tubular stem portion of the inlet nut. Theouter surface of the shaft has a generally frusto-conical shape thattapers down toward the discharge of the nozzle device. The inner surfaceof the hollow shaft has a cylindrical shape complementary to the stemportion upon which it rides. The inside surface of the tubular body hasa frusto-conical tapered shape complementary to the frusto-conical shapeof the outer surface of the shaft such that together they form abalancing chamber or passage therebetween.

The inlet nut and its stem portion each has a central bore therethroughthat directs fluid flow from a high pressure fluid source through thenut and stem portion and then through a spray jet head attached to thedischarge end of the shaft. The rotatable swivel shaft has a pluralityof passages, each extending through the shaft from the inner to theouter surface of the shaft to a circumferential channel in the outersurface. The channel joins helical grooves formed in the outer surfaceof the shaft. Fluid flow in these grooves during operation imparts arotational force on the shaft causing it to rotate about the stemportion of the inlet nut. Thus this rotational force eliminates the needfor providing offset angled ports in the spray head or nozzle tip. Thisallows driving the rotation of the shaft at a desired slower rotationspeed. Since the nozzle spray is directed out of the nozzle tip in adirection that is not offset from the longitudinal axis of the nozzle,rotation speed is not dependent on the pressure and flow rate throughthe nozzles. This same fluid flow, before reaching and exiting thehelical grooves, provides lubrication between first the stem portion ofthe inlet nut and the shaft and then between the inner surface of thehousing and the outer surface of the shaft such that solid bearings arenot required.

Embodiments of a fluid bearing nozzle assembly for spraying highpressure fluid in accordance with this disclosure each include a hollowcylindrical body, an inlet nut fastened to the cylindrical body, and ahollow tubular shaft member coaxially carried within the housing bodyand captured between the inlet nut and the body. The inlet nut has astem portion extending into a central bore through the shaft member. Thestem portion forms an inlet bearing area rotatably carrying the shaftmember thereon. The shaft member has an outlet end near an outlet end ofthe housing body that receives a spray head fastened thereto forrotation of the head with the shaft member. The inlet nut has a centralpassage to conduct fluid through the inlet nut to said outlet end of theshaft member.

An inner wall of the housing body and an outer portion of the shaft havecomplementary surface shapes together forming a regulating passagetherebetween. The shaft member has one or more bores communicatingbetween the inlet bearing area and the regulating passage, whereinpressure of fluid within the regulating passage acts axially upon theshaft to counter axial force on the shaft resulting from fluid pressureacting upon an inlet end of the shaft. Furthermore, the outer portion ofthe shaft has at least one helical groove there-around extending fromthe one or more bores along a substantial portion of the outer portionof the shaft. Fluid flow through the regulating passage and the helicalgroove imparts a rotational torque on the shaft to cause rotation of theshaft on the stem portion of the inlet nut.

In one embodiment the inner wall of the housing body and the outerportion of the shaft have complementary frusto-conical shapes. In thisembodiment there are one or more bores that communicate to an annularchannel in the outer surface of the shaft. The shaft has two counterrotating grooves around the shaft leading from the annular channel toopposite ends of the shaft. The fluid rotate in different directions inboth grooves, thereby generate torque on the shaft in only onedirection.

In another embodiment, the inner wall of the housing body has a steppedcylindrical shape with a large diameter portion and a small diameterportion with a shoulder therebetween. In this case, the shaft has acomplementary stepped cylindrical shape with a shoulder therebetween andthe one or more bores communicate with the shoulder of the shaft. Herethe shaft has a single helical groove that extends from the shoulderaround a substantial portion of the length of the large diameter portionof the shaft.

In each of these embodiments, a rear face of the shaft and the inlet nutform therebetween a balancing chamber. The hollow body has one or moreweep holes communicating with the balancing chamber for relieving fluidpressure from within the balancing chamber. Preferably the nozzle alsoincludes a cylindrical shroud fastened around the hollow body thatextends around a portion of the spray head. The weep holes in the hollowbody communicate between the balancing chamber and a gap between theshroud and the hollow body. This shroud primarily protects the rotatingspray head from damage and prevents contact between the spray head andthe object or surface being cleaned from stalling rotation of the head.

Further features, advantages and characteristics of the embodiments ofthis disclosure will be apparent from reading the following detaileddescription when taken in conjunction with the drawing figures.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of the nozzle device of one exemplaryembodiment in accordance with this disclosure.

FIG. 2 is a side view of the frusto-conical rotatable shaft removed fromthe nozzle device shown in FIG. 1.

FIG. 3 is a cross-section of a nozzle device of another exemplaryembodiment in accordance with the present disclosure.

FIG. 4 is a separate side view of a rotatable shaft removed from thenozzle device shown in FIG. 3.

FIG. 5 is a rear end view of the rotatable shaft shown in FIG. 4.

DETAILED DESCRIPTION

One embodiment of a nozzle device 100, as is shown in cross section inFIG. 1, has a generally cylindrical overall outer shape so that it canbe inserted into pipes and other tubular passages. The device 100 has ahollow tubular body 102 fastened to a high pressure inlet nut 104. Theinlet nut 104 is fastened to the body 102 preferably via a threadedconnection 106. Captured between the tubular body 102 and the inlet nut104 is a hollow, tapered, rotatable swivel shaft 108. The shaft 108 isrotatably supported on a tubular stem portion 110 projecting axially outof the inlet nut 104. The outer surface 112 of the shaft 108 has agenerally frusto-conical shape that tapers down toward the discharge ofthe nozzle device 100. The inner surface 118 of the shaft 108 has acylindrical shape complementary to the stem portion 110 upon which itresides. The inside surface 114 of the tubular body 102 has afrusto-conical tapered shape complementary to the frusto-conical shapeof the outer surface 112 of the shaft 108 such that together they form abalancing passage therebetween.

The stem portion 110 of the inlet nut 104 forms an inlet bearing areafor radially supporting the shaft 108. A spray jet head 116 is fastenedto the discharge or outlet end of the shaft 108, via conventional meanssuch as a threaded connection, so that both shaft 108 and head 116rotate together as an integral unit with the head 116 forming the nozzletip. The advantage here is that various different jet heads 116 may beattached to the shaft 108 depending on the particular cleaning task tobe performed.

The inlet nut 104 and its stem portion 110, have a central bore 111therethrough that directs fluid flow from a high pressure fluid sourcethrough the nut 104 into and through ports in the spray head 116. Therotatable swivel shaft 108 has a plurality of passages 120 therethrough,each extending from the inner surface 118 of the shaft 108 to the outersurface 112 of the shaft 108. These passages 120 exit into a preferablycentrally located circumferential channel 122 in the outer surface 112.The channel 122 joins counter-revolution helical grooves or channels 124and 126 formed in the outer surface 118 of the shaft 108. Groove 126spirals in a first direction around the shaft 108 toward the dischargeend of the shaft 108. Groove 124 spirals in an opposite second directionaround the shaft 108 toward the inlet end of the shaft 108.

During nozzle operation, these counter-revolution helical grooves 124and 126 act to impart a moment, or rotational force, to the shaft torotate the shaft 108 about the stem portion 110, and hence rotate thespray head 116. The shaft 108 in the device 100 effectively rotates atspeeds of preferably between about 2000 to 3000 rpm.

Finally, a tubular shroud 140 is preferably threadably fastened as asleeve over and to the housing body 102 to protect the spray head 116during insertion and retraction of the nozzle 100 from tubular passagesor vessels into which the nozzle device 100 is inserted. This tubularshroud 140 is fixed to the body 102 and does not rotate during nozzleoperation. Although not shown in FIG. 1, each of the threadedconnections also may preferably include an elastomeric seal ring betweenthe threaded relatively stationary parts to eliminate fluid leakagethrough the threaded connections between the various components. Theseinclude the threaded connections between head 116 and shaft 108, body102 and inlet nut 104, and shroud 140 to body 102.

During operation, high pressure fluid is introduced through the inletnut 104 into the central bore 111 in the inlet nut 104. This highpressure fluid passes through stem portion 110 into and through the head116. A portion of the high pressure fluid is redirected such that itleaks back (to the left in FIG. 1) around the stem portion 110constituting a leakage path 130 along the inlet bearing area, i.e., inthe clearance region between the outer surface of the stem portion 110and the inner surface 118 of the shaft 108. Part of this fluid passingthrough leakage path 130 flows into the annular chamber 121 between theinlet nut 104 and the shaft 108, and then out through weep holes 142into the gap 144 between the housing 102 and the shroud 140. Thisleakage fluid then flows to atmosphere via ports 145 to the open end ofthe shroud 140. Another portion of the fluid in leakage path 130 isdiverted outward through passages 120 in the shaft 108 to thecircumferential channel 122 formed in the outer surface of the shaft 108and thus into a frusto-conical tapered interface or balancing chamber146 formed between the inside surface 114 of the body 102 and the outersurface 112 of the shaft 108.

A portion of the fluid in channel 122 diverges and flows outward inopposite spiral directions through this balancing chamber 146, firstforward along helical groove 126 to exit the nozzle 100 around the head116 and also rearward along helical groove 124 to the clearance spacethat forms annular chamber 121 between the inlet nut 104 and the rearface of the shaft 108. This portion of the fluid then joins the portionof leakage 130 from along the stem 110 and passes through weep holes142, then passes out through ports 145 and the shroud 140 to atmosphere.

During operation, the shaft 108 becomes axially dynamically balanced onthe stem 110 such that mechanical bearings are not required. Thelubricity of the fluid flowing through these leakage paths 130 andthrough the balancing chamber 146 sufficiently supports and lubricatesthe shaft 108 and attached spray head 116 such that bearings are notrequired. Furthermore, the fluid flow through the helical grooves 124and 126 provides the rotational torque necessary to rotate the shaft 108and its attached spray head 116. This torque generating function isperformed by the leakage fluid flow. Therefore offset nozzle tips arenot necessary to rotate the nozzle head 116 as in previous designs.However, where higher rotational speed is desired, offset nozzle tipsmay be advantageously employed.

Another exemplary nozzle device 200 is shown in FIG. 3. The nozzledevice 200 operates in a similar manner to device 100. The device 200has a hollow tubular body 202 fastened to a high pressure inlet nut 204.The inlet nut 204 is fastened to the body 202 preferably via a threadedconnection 206. Captured between the tubular body 202 and the inlet nut204 is a hollow cylindrical, rotatable swivel shaft 208.

This shaft 208 is separately shown in side view in FIG. 4, and in a rearend view in FIG. 5. The shaft 208 is rotatably supported on a tubularstem portion 210 of the inlet nut 204 that projects axially from themain body of the inlet nut 204. The outer surface 212 of the shaft 208has a first cylindrical portion 213 and a reduced diameter cylindricalportion 214 forming an annular shoulder 215 therebetween. The insidesurface 214 of the tubular body 202 has a shape complementary to thestepped cylindrical shape of the outer surface 212 of the shaft 208 suchthat together they form a balancing passage therebetween.

The inner surface 218 of the shaft 208 forms a straight bore that has acylindrical shape complementary to that of the stem portion 210 uponwhich it resides. A rear end, or inlet view, of the shaft 208 is shownin FIG. 5. The central bore 218 is surrounded by an annular recessforming part of the balancing chamber 221. The interior sides of thisrecess around the bore 218 are straight so as to form a hexagonal nutshape used to hold the shaft 208 during assembly and disassembly of theshaft 208 to the spray head 216.

The stem portion 210 of the inlet nut 204 forms an inlet bearing areafor radially supporting the shaft 208. A spray jet head 216 is fastenedto the discharge or outlet end of the shaft 208, via conventional meanssuch as a threaded connection, so that both shaft 208 and head 216rotate together as an integral unit with the head 216 forming the nozzletip. The advantage here is that various different jet heads 216 may beattached to the shaft 208 depending on the particular cleaning task tobe performed.

The inlet nut 204 and its stem portion 210, has a central bore 211therethrough that directs fluid flow from a high pressure fluid source,through the nut 204, the bore 211, and then into and through ports 217in the spray head 116. The rotatable swivel shaft 108 has a plurality ofpassages 220 therethrough, preferably at least two, each extending fromthe inner surface 218 of the shaft 208 to the outer surface 212 of theshaft 208. These passages 220 exit into an annular space or chamber 222formed between the shoulder 215 and a complementarily shaped innershoulder surface 223 of the housing 202. The single helical groove 224communicates with this space 222. Groove 224 spirals around the shaft208 from the space 222 toward the inlet end of the shaft 208. Thedirection of the helical groove 224 determines the direction of rotationof the shaft 208, and hence the rotary spray head 216. For example, ifthe groove 224 spirals clockwise from the space 222 around the shaft 208toward the inlet end of the shaft 208, then rotation will becounterclockwise.

Finally, a tubular shroud 240 is preferably threadably fastened as asleeve over and to the housing body 202 to protect the spray head 216during insertion and retraction of the nozzle 200 from tubular passagesor vessels into which the nozzle device 200 is inserted. This tubularshroud 240 is fixed to the body 202 during nozzle operation and does notrotate.

At the rear of the swivel shaft 208 in the space between the inlet nut204 and the shaft 208 are a pair of weep holes 226 that lead from thisspace through the housing 202 into an annular gap 228 between thehousing 202 and the shroud 240. The space between the inlet nut 204 andthe shaft 208 forms a balancing chamber 221. Fluid that enters this gap228 then flows to the atmosphere behind the rotary head 216 throughpassages 232 in the housing 202.

The threaded connections between the housing 202 and the shroud 240includes two elastomeric seal rings 250. These outer seal rings 250 seeonly low pressure leak water. An inner seal ring 250 is provided aroundthe rear end portion of the spray head 216 between the threadedconnection to the shaft 208. This seal ring 250 sees full high operatingfluid pressure. These seal rings 250 prevent fluid leakage past thethreaded connections during high pressure operation of the nozzle device200 and ensure that all the fluid flows either through the usefulpassages and leakage paths as described herein or through the spray headdirectly.

During operation, high pressure fluid is first introduced through theinlet nut 204 into the central bore 211 in the inlet nut 204. This highpressure fluid passes through stem portion 210 into and through the head216. A portion of the high pressure fluid is redirected such that itleaks back (to the left in FIG. 3) around the stem portion 210,constituting a leakage path 230 along the inlet bearing area, i.e., inthe clearance region between the outer surface of the stem portion 210and the inner surface 218 of the shaft 208.

Part of this fluid passing through leakage path 230 flows into thebalancing chamber 221 between the inlet nut 204 and the shaft 208, andthen out through weep holes 226 into the gap 228 between the housing 202and the shroud 240. This leakage fluid then flows through passages 232to atmosphere via the open end of the shroud 240. Another portion of thefluid in leakage path 230 is diverted forward and outward through thepassages 220 in the shaft 208 to the space 222. From the space 222, mostof this portion of leakage fluid then flows through the helical groove224 to the balancing chamber 221. A small portion of leakage fluid flowstoward the head 216 through the annular clearance space between thereduced diameter portion 214 of the shaft 208 and the housing 202.

During operation, the shaft 208 becomes axially dynamically balanced onthe stem 210 such that mechanical bearings are not required. Thelubricity of the fluid flowing through these leakage paths 230 andthrough the balancing chamber 221 sufficiently supports and lubricatesthe shaft 208 and attached spray head 216 such that bearings are notrequired. Furthermore, the fluid flow through the helical groove 224provides the rotational torque necessary to rotate the shaft 208 and itsattached spray head 216. This torque generating function is performedentirely by the leakage fluid flow. Therefore offset nozzle tips are notnecessary to rotate the nozzle head 216 as in previous designs. However,where high rotational speed is desired, offset nozzle tips may also beadvantageously employed in these embodiments, since the head 116 and 216are interchangeable with other head designs.

Balancing in this embodiment 200 occurs because, as the fluid pressurein the space 222 exerted by the leakage fluid increases, an axial forcepushes the shaft 208 rearward, or to the left in FIG. 3. When thisoccurs, the rear end of the shaft 208 partially closes off the weepholes 226. This reduces the leakage rate, which in turn increases theaxial pressure acting on the left end of the shaft 208 in opposition tothe axial force exerted in space 222 until a balance between the axiallyopposing forces is achieved.

In this embodiment 200, it is therefore the interaction of the rear faceof the swivel shaft 208 with the opening to the weep holes 228 thatactually regulates the balancing of axial forces during nozzleoperation. The presence of the helical groove 224 determines thedirection of and speed of rotation of the swivel shaft 208. Thedimensions of the space between the shaft 208 and housing 202, and theinner wall of the shaft 208 and the outer wall of the stem 210 are suchthat a clearance of between 0.0005 and 0.0010 is preferred.

In accordance with the features and benefits described herein, thepresent invention is intended to be defined by the claims below andtheir equivalents.

What is claimed is:
 1. A fluid bearing nozzle assembly for spraying highpressure fluid comprising: an inlet nut; a hollow cylindrical body; anda hollow tubular shaft member coaxially carried within the hollowcylindrical body and captured between the inlet nut and the body, one ofthe inlet nut and the hollow cylindrical body having a stem portionextending into a central bore, the stem portion forming an inlet bearingarea rotatably carrying the shaft member thereon, the shaft memberhaving an outlet end near an outlet end of the housing body, the outletend of the shaft member receiving a spray head fastened thereto forrotation of the head with the shaft member, said inlet nut having acentral passage to conduct fluid through the inlet nut to said outletend of the shaft member; an inner wall of the hollow cylindrical bodyand an outer portion of the shaft having complementary surface shapestogether forming a regulating passage therebetween, said shaft memberhaving one or more bores communicating between the inlet bearing areaand the regulating passage, wherein pressure of fluid within theregulating passage acts axially upon the shaft to counter axial force onthe shaft resulting from fluid pressure acting upon an inlet end of theshaft, and wherein the outer portion of the shaft has a helical groovethere-around extending from the one or more bores along a substantialportion of the outer portion of the shaft and wherein fluid flow throughthe regulating passage and the helical groove imparts a rotationaltorque on the shaft to cause rotation of the shaft on the stem portionof the inlet nut.
 2. The nozzle according to claim 1 wherein the innerwall of the hollow cylindrical body and the outer portion of the shafthave complementary frusto-conical shapes.
 3. The nozzle according toclaim 2 wherein the one or more bores communicates to an annular channelin the outer surface of the shaft and the shaft has two counter rotatinggrooves around the shaft leading from the annular channel to oppositeends of the shaft.
 4. The nozzle according to claim 1 wherein the innerwall of the hollow cylindrical body has a stepped cylindrical shape witha large diameter portion and a small diameter portion with a shouldertherebetween.
 5. The nozzle according to claim 4 wherein the shaft has acomplementary stepped cylindrical shape with a shoulder therebetween andthe one or more bores communicate with the shoulder of the shaft.
 6. Thenozzle according to claim 5 wherein the shaft has a single helicalgroove that extends from the shoulder around a substantial portion ofthe length of the large diameter portion of the shaft.
 7. The nozzle ofclaim 1 wherein a rear face of the shaft and the inlet nut formtherebetween a balancing chamber and wherein the hollow body has one ormore weep holes communicating with the balancing chamber for relievingfluid from within the balancing chamber.
 8. The nozzle of claim 7further comprising a cylindrical shroud fastened around the hollow bodythat extends around a portion of the spray head, wherein the weep holesin the hollow body communicate between the balancing chamber and a gapbetween the shroud and the hollow body.
 9. The nozzle of claim 8 whereinfluid in the gap is relieved to atmosphere through at least one passagebetween the shroud and the housing body.
 10. The nozzle of claim 7wherein the balancing chamber and regulating passage connect togetherand a portion of fluid flow through the central bore flows along theinlet bearing area to the balancing chamber and to the regulatingpassage.
 11. A nozzle assembly for spraying high pressure fluid againstan object comprising: a hollow cylindrical body; an inlet nut; a hollowtubular shaft member coaxially carried within the housing body andcaptured between the inlet nut and the body, the inlet nut having a stemportion extending into a central bore through the shaft member, the stemportion forming an inlet bearing area rotatably carrying the shaftmember thereon, the shaft member having an outlet end near an outlet endof the hollow cylindrical body, the outlet end of the shaft memberreceiving a spray head fastened thereto for rotation of the head withthe shaft member, said inlet nut having a central passage to conductfluid through the inlet nut to said outlet end of the shaft member; anda tubular shroud around the hollow body and the shaft member, the shroudfastened to a portion of the hollow body; an inner wall of the housingbody and an outer portion of the shaft having complementary surfaceshapes together forming a regulating passage therebetween, said shaftmember having one or more bores communicating between the inlet bearingarea and the regulating passage, wherein pressure of fluid within theregulating passage acts axially upon the shaft to counter axial force onthe shaft resulting from fluid pressure acting upon an inlet end of theshaft, and wherein the outer portion of the shaft has a helical groovethere-around extending from the one or more bores along a substantialportion of the outer portion of the shaft and wherein fluid flow throughthe regulating passage and the helical groove imparts a rotationaltorque on the shaft to cause rotation of the shaft on the stem portionof the inlet nut.
 12. The nozzle according to claim 11 wherein the innerwall of the hollow cylindrical body and the outer portion of the shafthave complementary frusto-conical shapes.
 13. The nozzle according toclaim 12 wherein the one or more bores communicates to an annularchannel in the outer surface of the shaft and the shaft has two counterrotating grooves around the shaft leading from the annular channel toopposite ends of the shaft.
 14. The nozzle according to claim 11 whereinthe inner wall of the housing body has a stepped cylindrical shape witha large diameter portion and a small diameter portion with a shouldertherebetween.
 15. The nozzle according to claim 14 wherein the outersurface of the shaft has a complementary stepped cylindrical shape witha shoulder therebetween and the one or more bores communicate with theshoulder of the shaft.
 16. The nozzle according to claim 15 wherein theshaft has a single helical groove that extends from the shoulder arounda substantial portion of the length of the large diameter portion of theshaft.
 17. The nozzle of claim 11 wherein a rear face of the shaft andthe inlet nut form therebetween a balancing chamber and wherein thehollow body has one or more weep holes communicating with the balancingchamber for relieving fluid from within the balancing chamber.
 18. Thenozzle of claim 17 wherein the balancing chamber and regulating passageconnect together and a portion of fluid flow through the central boreflows along the inlet bearing area to the balancing chamber and to theregulating passage.
 19. A nozzle assembly for spraying high pressurefluid against an object comprising: a hollow cylindrical body; an inletnut; a hollow tubular shaft member coaxially carried within the housingbody and captured between the inlet nut and the body, the inlet nuthaving a stem portion extending into a central bore through the shaftmember, the stem portion forming an inlet bearing area rotatablycarrying the shaft member thereon, the shaft member having an outlet endnear an outlet end of the hollow cylindrical body, the outlet end of theshaft member receiving a spray head fastened thereto for rotation of thehead with the shaft member, said inlet nut having a central passage toconduct fluid through the inlet nut to said outlet end of the shaftmember; and a tubular shroud around the hollow body, the shroud fastenedto a portion of the hollow body; an inner wall of the housing body andan outer portion of the shaft having complementary surface shapestogether forming a regulating passage therebetween, said shaft memberhaving one or more bores communicating between the inlet bearing areaand the regulating passage, wherein pressure of fluid within theregulating passage acts axially upon the shaft to counter axial force onthe shaft resulting from fluid pressure acting upon an inlet end of theshaft, and wherein the outer portion of the shaft has a helical groovethere-around extending from the one or more bores along a substantialportion of the outer portion of the shaft and wherein fluid flow throughthe regulating passage and the helical groove imparts a rotationaltorque on the shaft to cause rotation of the shaft on the stem portionof the inlet nut, and wherein a portion of fluid flow through theregulating passage passes through one or more weep holes through thehousing body to a gap formed between the housing body and the shroud,wherein a rear face of the shaft and the inlet nut form therebetween abalancing chamber communicating with the one or more weep holes forrelieving fluid from within the balancing chamber.
 20. The nozzleaccording to claim 19 wherein the inner wall of the hollow cylindricalbody and the outer portion of the shaft have complementaryfrusto-conical shapes.